DESC:
[0037] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0038] In the following detailed description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.

[0039] Referring to the accompanying drawings, and particularly to FIG.1, a shock wave assisted fracking apparatus is provided, according to one embodiment of the present disclosure. A shock wave is a strong pressure wave that is often associated with sudden release of massive amount of energy, such as an explosion. The shock waves move at a speed greater than the local speed of sound (supersonic speed) and have the capability of instantaneously raising the magnitudes of the static properties of the medium through which it travels, such as pressure, temperature, density etc. The impulse generated by these waves is used for a variety of applications, one being in fracking of oil wells. Fracking involves creation and widening of cracks in the rocks/rock beds surrounding the well to replenish the oil content in the well to improve the yield. As a prerequisite to fracking process, the oil wells are usually filled with water or brine as a safety measure to counteract the high pressures generated when an oil or gas reserve is reached with the cracks.
[0040] According to one embodiment of the present disclosure, the apparatus comprises a shock tube 102, a coiled tubing unit (CTU) 104, high-speed valve 106 and one or more batteries 108. The apparatus further comprises a signal receiver 110, an inflatable packer 112, a check valve 114 and a perforated tube 116.
[0041] According to one embodiment of the present disclosure, the shock tube 102 is used for generating plurality of shock waves in pressurized gases in a controlled manner. The shock tube is a long tubular structure capable of holding gas used for generating shock waves. The shock tube is compartmentalized in two distinct sections called a driver section 118 and a driven section 120. The two sections of the shock tube are separated using a diaphragm or a high-speed valve 106. The driver section 118 holds a gas at high pressure (about 400 bar) whereas the driven section 120 contains gas at a comparatively low pressure as compared to the gas in the driver section 118. FIG. 2 illustrates a cross sectional view of the shock wave assisted fracking apparatus, according to one embodiment of the present disclosure.
[0042] The CTU 104 provided in the apparatus is configured for supplying high pressure gas such as nitrogen gas in the larger depths of oil wells. The nitrogen gas is supplied from the ground surface level. A long continuous metal tube provided in the CTU 104 delivers this nitrogen gas to the depths of the oil well at pressures as high as about 400 bars. This nitrogen gas is then used as a driver to generate the plurality of shock waves in the driven section 120. The CTU 104 is directly connected to the driver section 118 of the shock tube 102.
[0043] According to one embodiment of the present disclosure, the high-speed valve (HSV) 106 constitutes a junction between the driver section 118 and driven section 120 of the shock tube 102. FIG. 3 illustrates a schematic diagram 302 and a cross sectional view 304 respectively of the high-speed valve used in the shock wave assisted fracking apparatus, according to one embodiment of the present disclosure. The HSV 106 is operated every time a shock wave generation is desired. The HSV 106 is configured for operating in a very short span of time (of the order of about 2 milliseconds) which assures the generation of a stronger shock wave. The HSV 106 is electrically actuated and designed in a manner to fit within the inner diameter of the production tube (a tube with diameter of about 55 to 60 mm used in oil well bores for extracting oil) of the oil well. The various parts of the HSV 106 are shown in FIG. 3 which are an inlet cylinder (306), a center cylinder (308), a cup (310), a cup holder (312) and an outlet cylinder (314).
[0044] According to one embodiment of the present disclosure, one or more batteries 108 are incorporated into the apparatus as obtaining electrical connection for actuation of the HSV 106 from the ground level to the depths within the oil well is tedious. Lithium polymer batteries are preferred for this purpose as these batteries deliver a reasonable voltage and current rating while maintaining a small size so as to fit within the apparatus. Each such battery provides a voltage of about 3.7 volts (V) and hence multiple batteries are connected in series and parallel to meet the power requirement for operating the HSV 106. The number of batteries used depends on the number of times the HSV 106 is operated before being retracted from the oil well. These batteries are wrapped along the length of the shock tube 102 to save on available space. FIG. 4 illustrates a schematic diagram depicting various ways for arranging batteries around the driver section of the shock tube, according to one embodiment of the present disclosure. A suitable casing 402 is provided over the batteries to shield it from the water or brine filled in the well.
[0045] According to one embodiment of the present disclosure, an inflatable packer 112 is used for isolating the area that is affected by the shock waves. The use of inflatable packer 112 is critical especially in brine filled wells and aids in segregating the supplied energy within a small volume near the well wall cracks. The gas required to inflate these packers 112 is supplied from the driver section 118 of the shock tube 102 using appropriate valves and regulators. FIG. 5 illustrates the various views of the inflatable packer 112 used in the shock wave assisted fracking apparatus, according to one embodiment of the present disclosure. As shown, the inflatable packer 112 comprises a metal section 502 that constitutes the spine and a rubber section 504 that inflates outwards. The distance of inflation and pressure rating vary depending on the design of the packer.
[0046] The check valve 114 provided in the apparatus is a non-return type one-way valve which opens up automatically when the internal pressure within the shock tube 102 goes higher than the external pressure. The check valve 114 is attached to the end of the driven section 120, thereby isolating the column of gas within the driven section 120 to facilitate formation of the shock waves. One side of the check valve 114 (connected to the driven section 120) is configured for holding gas and the other side touches the water/brine within the oil well. On generation of the shock wave within the driven section 120, the increased pressure mechanically opens up the check valve 114 and escapes outwards into the water/brine. The check valve 114 closes automatically once the pressure on both sides equalizes. The check valve 114 is configured for operating in only one way so as to negate any chance of reverse flow of the water/brine into the shock tube 102.
[0047] A perforated tube 116 is provided at the bottom of the check valve 114 which houses perforations that are directed towards the wall cracks. This perforated tube 116 is configured for releasing the high-pressured shock waves on to the rocks or rock beds. The perforations provided in the perforated tube 116 aids in directing the gas pressure towards the cracks in lateral direction, thereby resulting in fracking.
[0048] FIG. 6 illustrates a flow chart explaining a method of fracking rocks/rock beds using the shock wave assisted fracking apparatus, according to one embodiment of the present disclosure. The method envisaged by the present disclosure is an eco-friendly method for fracking of oil wells as it does not require extensive usage of water and prevents contamination of underground water reserves in the vicinity of rock beds. Further, the shock wave assisted fracking method of the present disclosure requires reduced usage of water resources as it does not involves use of pressurized water for crack formation and propagation (as used in hydrofracking) but instead makes use of pressurized gases.
[0049] In accordance with the present disclosure, the shock wave assisted method for creating and expanding cracks in oil wells includes inserting the shock wave assisted fracking apparatus into the oil well bore for generating plurality of shock waves in a controlled manner (602). Each shot with the apparatus is initiated manually from the ground level by the press of a button. This signal is transmitted from the surface level to the depths of the oil well using either electromagnetic waves (in case the well is filled with water) or acoustic waves (in case the well is filled with brine) (604). A signal receiver 110 in the apparatus receives this signal and actuates a relay which in turn operates a high-speed valve 106 (606) or diaphragm provided in the apparatus.
[0050] Further, when the diaphragm ruptures, or the high-speed valve 106 is opened up, a strong shock wave is generated within the driven section 120 of the apparatus which raises the pressure and temperature of the gas within it. The diaphragm is ruptured to produce a series of shock waves (608). The pressurized driven section gas (gas jet) is ejected through the perforated tube 116 into the water or brine within the well at a location in the vicinity of the cracks on walls surrounding the oil well (610). Since the gas jets are directed towards the crack orientation, the sudden pulse of increased pressure extends the cracks to longer distances in a controlled manner.
[0051] According to an embodiment of the present disclosure, the shock waves travelling through the driven section 120 of the shock tube 102 are directed to the locations where crack formation or widening of existing cracks is desired. The pressure creates the cracks in the rock beds. In case of the existing cracks, the high-pressure shock waves penetrate through the crack thus widening and extending the cracks.
[0052] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims. ,CLAIMS:What is claimed is:
1. A shock wave assisted apparatus for fracking of rock beds and also for widening of the existing cracks in the rock beds, the apparatus comprising of:
a shock tube that is separated into at least two sections and the first section or the top section is termed as a driver section and the second section or the bottom section is termed as a driven section;
an electrically actuated diaphragm or a high-speed valve that separates the driver section and the driven section;
a high-pressure gas to be held in the driver section;
a low-pressure gas to be held in the driven section;
a coiled tubing unit for supplying high pressure gas such as but not limited to nitrogen gas into the driver section of the shock tube through a metal tube;
one or more batteries for powering means;
a signal receiver to transmit radio signals;
a inflatable packer to isolate the area affected by shock waves;
a check valve to release the internal pressure in the shock tube; and
a perorated tube provided at the bottom of the check valve which houses perforations that are directed towards the wall cracks.
wherein, the shock wave tube is inserted into the well, thereby a signal is transmitted from the surface level to the shockwave tube which on recipient of the signal actuates the relay to operate a high-speed valve or rupture a diaphragm for generating series of multiple shock waves and direct the high-pressure shock waves through the perforated tube at a location where crack formation or widening of existing cracks is required.

2. The apparatus of claim 1, wherein the shock tube is at least a long tubular structure capable of holding gases used for generating shock waves.
3. The apparatus of claim 1, wherein the high-speed valve constitutes junction between the driver section and the driven section of the shock tube.
4. The apparatus of claim 1, wherein the electrically actuated high-speed valve comprises of a inlet cylinder, a center cylinder, a cup, a cup holder and an outlet cylinder.
5. The apparatus of claim 1, wherein the electrically actuated high-speed valve is powered by one or more batteries such as but not limited to the use of lithium polymer batteries.
6. The apparatus of claim 1, wherein the inflatable packer is inflated by a gas provided from the driver section of the shock tube through appropriate valves.
7. The apparatus of claim 1, wherein the inflatable packer comprises of a metal section and constitutes a spine and a rubber section that inflates outwards wherein the distance of inflation and pressure rating may vary depending on the design of the packer.
8. The apparatus of claim 1, wherein a non-return type one-way check valve is provided at the end portion of the driven section which opens up automatically when the internal pressure within the shock tube goes higher than the external pressure.
9. The apparatus of claim 1, wherein one side of the check valve is configured for holding the gas and the other side of the valve touches the water or brine within the oil well and on generation of the shock wave within the driven section, the increased pressure mechanically opens up the check valve and escapes outwards to the water or brine.
10. The apparatus of claim 1, wherein the perforated tube is provided at the bottom of the check valve which houses perforations that are directed towards the wall cracks and is configured for releasing high pressured shock waves onto the rocks and rock beds and the perforations provided in the perforated tube aids in directing the gas pressure towards the cracks in lateral direction.